The background art related to cooling of electricity storage devices includes, for instance, the technologies disclosed in patent literature 1 and patent literature 2.
Patent literature 1 discloses a technology whereby numerous battery modules disposed in parallel within a holder case are evenly cooled by installing a regulating means within the holder case so as to achieve a higher airflow velocity on a downstream side than on an upstream side for air flowing inside the holder case. Patent literature 2 discloses a technology whereby differences in temperature among the various battery module groups is minimized by setting a ratio of “a”, representing the clearance between the outer circumferential surfaces of two rod-like battery modules adjacent to each other within a battery module group located closest to a cooling air introduction port, and “b”, representing the clearance between the outer circumferential surfaces of a rod-like battery module in the battery module group closest to the cooling air introduction port and a rod-like battery module in a battery module group adjacent to the battery module group closest to the cooling air introduction port, to a value within a predetermined range.